Flush receptacle



p 19, 1933. M. N. RUSSELL 1,927,245

FLUSH RECEPTACLE Filed Sept. 23 1926 avwcnto'c Patented Sept. 19, 1933 UNITED STATES PATENT OFFICE Pass & Seymour, Inc.,

ration of New York Solvay, N. Y., a corpo- Application September 23, 1926 Serial No. 137,369

14 Claims.

This invention relates to separable connectors and more particularly to flush receptacles and attachment plugs for use therewith.

It is a general object of the present invention to provide a novel and improved flush receptacle together with a three bladed cap or attachment plug, the receptacle being adapted to receive either this special three bladed plug or the standard two bladed plug having parallel blades.

Another object of the present invention consists in the provision of a fiush receptacle adapted to receive a three bladed plug and having a contact connected to the mounting strap of the receptacle whereby it will be grounded to the conduit thru the box in which it is mounted.

A further object of the present invention consists in the provision of a flush receptacle provided with three contact springs, two of which are so spaced as to be adapted to receive and contact with the blades of a standard two bladed plug and the third of which is adapted to be grounded and to contact with a third blade on a special plug when used on the cord of a portable receptacle of which it is desired to ground the metal parts.

Still another object of the present invention consists in the provision of a flush receptacle having a novel construction wherein the binding terminals and the spring contacts are held in resilient engagement with each other and thus retained in position whereby they may readily be assembled or disassembled.

Other and further objects in the construction, arrangement and combination of the various parts will be apparent to those skilled in the art by a consideration of the accompanying drawing and following specification wherein is described by way of example only a single embodiment of the present invention with the understanding that various changes may be made therein without departing from the spirit of the invention or the scope or" the appended claims.

In said drawing:

Fig. 1 is a front elevation of a flush receptacle constructed according to the present invention;

Fig. 2 is a longitudinal vertical section on line 2-2 of Figure 1;

Fig. 3, is a rear elevation showing the mounting strap in section on line 3-3 of Figure 2, with the box removed and disclosing the back insulation sheet partly broken away;

Fig. 4 is a transverse section on line 4-4 of Figure 1;

Fig. 5 is a side elevation of the three bladed plug adapted for use with the flush receptacle shown;

Fig. 6 is a plan view thereof looking from the blade end; and

Fig. 7 is a view similar to Figure 6 of a standard two bladed plug.

' In a number of States and in the larger cities, the local ordinances require that one conductor of a pair leading to all outlets be grounded, and

that this particular grounded wire be connected to certain portions of all electrical fixtures, to which end the Board of Underwriters have drawn up a code requiring that binding terminals of sockets and other outlets be properly designated in order that the grounded wire may be connected to that portion of the outlet which is most likely to be touched by a person in using the outlet. For instance, the screw shell of a socket is connected to the grounded side of the line. No matter what care is used in providing such a grounded circuit, the effort is wasted where portable devices are used for no attempt is made, under ordinary circumstances, to use a polarized attachment plug or to so wire up the cord of the portable as to insure the proper side thereof being grounded. Furthermore the frame or other metal parts of the portable cannot be grounded by the use of the usual two wire cords, as are all the parts of a stationary device such as a flush receptacle, a chandelier and the like by virtue of the conduit and fitting on which they are mounted.

Extreme care is-taken in most localities to insure the electrical continuity of a conduit and of the boxes attached thereto in order that exposed metal parts may at all times be at ground potential. The present invention contemplates the extension of such protection to all portable devices and at the same time provides for interchangeability of attachment plugs during the transition period whereby the change may be made without rendering any present equipment obsolete.

The invention will be described in conjunction with a flush receptacle and attachment plug for use with the same, although it may be adapted for many other purposes which will be readily understood by those skilled in the art.

Referring to the drawing there is disclosed at 10 a unitary block of insulation such as porcelain, or similar material. which may be formed by molding or in any suitable manner. The insulation block is adapted to be mounted in the usual outlet box 10' and for this purpose is provided with the mounting strap 11 having elongated holes 12 to receive screws which pass into struckout ears on the outlet box. The general outline of the block 10 is conventional and it is provided with the 'projected face 13 adapted to pass through the central opening in the usual flush plate, not shown, which plate may be secured in position by screws passing into the threaded openings 14 in the mounting strap.

The block 10 is substantially rectangular in form, its rear face 15 being parallel to the front face 16 and to the outer surface of the projected face 13. It is somewhat elongated having the flat ends 17 and the flat sides 18 bulged somewhat at their centers as at 19 near the face 13 only.

On either side of a median plane thru the face 13 is provided a passageway 20 extending from the front to the rear face of the block. The outline of the front opening of each of these passages is such as to freely receive the blade or prong 21' of a standard attachment plug of the parallel blade type, as shown in Figure '7 and the spacing of these openings is proper to accommodate the two prongs on the standard plug. It will be understood that by standard plug is meant the type of attachment plug such as shown in Figure 7, at present supplied with most portable devices and which is universally adapted to be received in flush receptacles having parallel or T slots and into screw plugs having similar slots. The passageways 20 are symmetrically disposed on the face 13 in such a manner that the minor axes thereof are coincident with an axis of the face. In the event the face is circular. as shown, these minor axes are coincident with a diameter such as that defined by the line 4-4 in Figure 1 of the drawing. The configuration of the passages 20 below the surface 13 may best be seen in Figure 4. The passages being identical but reversed in position, it is deemed necessary to describe but one. It will be seen that the outer wall 21 is contiguous with the wall of the opening 20 for a major portion of the distance through the block whereas the inner wall 22 although parallel to the wall 21 is further spaced from the same than at the opening, providing the shoulder 23 just inside of the opening 20. This wall 22 extends clear to the back of the block. Near the rear end the wall 21 stops and the passage is enlarged from there to the outer side of the block and the wall 24 forms the outer boundary wall thereof. In plan, the rear end of the passage is rectangular having its major axis however at right angles to the major axis of the opening 20.

In each passage 20 through the block is provided a contact spring generally indicated by the reference character 25 and having the bowed or arcuate portion 26, the end of which abuts the shoulder 23 when the spring is properly positioned. This shoulder assists in assembling the device and increases the tension of the spring. The upper end of the spring is bent over at right angles to the chord of the bow 26, as shown at 27, and when in position is parallel to the rear face of the block and slightly below the same. The portion 28 is arranged at right angles to the portion 27 and extends alongside of and parallel to the wall 24 but spaced therefrom. The distance between the center of the bow 26 and the wall 21 is less than the thickness of one of the blades of an attachment plug and the bow is preferably provided with a boss 29 to be received in the customary perforation 66 in the blade to prevent the same from falling or being too readily drawn out.

A recess 30 of irregular form is provided adjacent the rear of the passage and opening into the side of the block and is adapted to accommodate portions of the binding terminal, as shown best in Figure 3. The binding terminal comprises a metal strap or sheet having a substantially rectangular wing portion 31 received between end 28 of the spring and the wall 24 and tightly held therein by the resilience of the spring. Its lower edge fits into a slight channel or groove 32 which prevents the same from being displaced. The terminal is offset as at 33, which offset portion passes directly outwardly through i the connecting passage between the recess 30 and the spring passage 20. The terminal is again bent so that its portion 34is parallel to the portion 31 but offset outwardly therefrom. This portion 34 as well as the portion 33 has its lower edge in a groove or channel. The outer face of the portion 34 is substantially flush with the outer side face 18 of the block and its end rests in the depression 35. A binding screw 36 passes through the portion 34 and its inner edge is received in a suitable extension in the recess 30. From this construction it will be seen that the spring and binding terminal mutually assist in holding each other in position against movement in any direction except directly toward the rear of the block. To prevent such movement an insulation sheet 39 substantially rectangular in form, with two reentrant corners, is fitted into the shallow depression 3'7 in the back of the block. This depression extends the full width of the block over the back of the contact springs and terminals and extends upwardly above these terminals where it has a narrowed portion 38. The insula tion sheet 39 fits into this depression and is secured therein, as will be later described, thus retaining not only the contact springs but the binding terminals securely in position.

A third passage through the block is provided at 40. This passage opens into the face 13 as do the passages 20 and has the same shape at the face. It is however arranged at right angles to the passages 20 and is bisected by the median line between these passages. Its outer wall 41 is continuous and fiat clear through the block but its inner wall 42 is so offset as to form a shoulder 43.

A third or grounding spring 44 is provided in this passage with its outer end against the shoulder 43 and its central portion bowed, as shown at 45, in the same manner as the central portion of the two other springs so as to engage with the blade on a special plug presently to be described. The rear end of the spring 44 passes through a narrow slit 46 in the insulation sheet 39. This slit is positioned adjacent the wall 42. Outside of the insulation sheet the spring is'bent at right angles and extends outwardly along the outer face of the insulation sheet 39 as best shown at 4'? in Figure 3.

Suitable hollow rivets 48 are secured in the material of block 10 and project slightly beyond the rear face thereof, one near either end. The

portion 47 of the grounding spring 44 is perfo-' rated as at 49 to be received over one of these rivets 48 where the portion 47 extends beyond the end of the insulation sheet.

The mounting strap 11 has two portions 50 which pass down through the grooves 50 in the ends of the block 10 and these portions 50 are connected by an integral portion 51 which passes over the back of the insulation block. This portion is perforated and receives through the perforations the rivets 48. After the strap is in position, the rivets are headed over as at 52 and serve to securely fasten the mounting strap to the block. The mounting strap portion 51 fits in shallow channels 53 in the back of the block so that its center portion presses tightly on the insulation sheet and securely holds it in position, it being held against lateral movement by being recessed in the back of the block. The mounting strap rests on top of the portion 4'1 of the grounding spring and securely holds the same in position and is in electrical engagement therewith. This insures that when the block is mounted in an outlet box that the spring 44 will be in electrical contact with the conduit system of which the box forms a part. The grounding of the spring 44 is not left to chance nor to the discretion of the workman but it is automatically and positively grounded upon the mounting of the receptacle in the box.

A special plug is adapted for use with the receptacles above described and it is shown in Figures 5 and 6. It comprises the usual insulation block or base 60 having a central passage or opening 61 to receive the cord, and provided with the parallel spaced blades 62 as on the conventional plug disclosed in Figure 7. Suitable binding terminals 63 are provided for these blades 62. In addition a third blade 64 is provided having a binding terminal 65. This blade is adapted to be received in the passage 40 in the above described flush receptacle, and to contact with the grounding spring 44.

In attaching such a plug to a portable device a three conductor cord is used, two of the conductors being connected in the conventional manner to the blades 62 and to the binding terminals of the portable device while the thirdconductor is connected to the blade 64 and at the portable device to the exposed metal or other conducting parts of the frames to insure that these parts are at ground potential at all times and to prevent shock to persons handling the same in case of defective wiring or insulation leaks in the portables. The position of the passages 20 and 40 is suchthat the plug can be inserted in but a single position thus insuring that the portable will always be properly connected and always have its frame grounded.

Flush receptacles of the type described may be provided in new structures in lieu of the conventional two contact type. By the provision of such receptacles however the use of conventional attachment plugs is not precluded and since at present portables are provided with such plugs the value of this arrangement will be evident. Such portables as are not provided with three prong plugs may be still used with the present type of receptacle but where extreme care is desired and insurance against trouble, the three prong plugs can be provided to thus insure grounding of the frames of all portables.

Where during the transition period receptacles of the present type are usedwith the conventional two-bladed plug, it will be seen that owing to the symmetrical disposition of the openings 20 for the blades of this plug the cap of the plug will be concentric to the periphery of the face 13 and present the same appearance as such a cap would if used with a standard two-opening convenience outlet.

Having thus described the invention what is claimed as new and desired to be secured by Letters Patent is:

1. In a flush receptacle adapted to receive a plug having a fiat blade, in combination, an insulation block having a recess opening on the front face thereof of a size to receive a plug blade, the back face thereof having a recess communicating with said first recess but larger in cross section, one wall of each recess being common, said second recess being enlarged in one direction adjacent said back face, a spring having a bowed portion in said second recess, an angular portion on said spring in the enlargement of said second recess and a binding terminal having an arm in said enlargement to retain said spring therein.

2. In a flush receptacle adapted to receive a plug having a flat blade, in combination, an insulating block having parallel front and back faces with a passage leading from one face to the other, said passage at the front face being of a size to accommodate a plug blade, said passage being larger below the front face, a contact spring having a bowed portion in said enlargement, a substantially U-shaped end on said spring, a further enlargement in said passage at the back face toreceive said spring end, a terminal contact, a wing thereon fitting in said further enlargement and pressing both ends of said bowed portion of said spring against a wall of said passage.

3. In a flush receptacle adapted to receive a plug having a fiat blade, in combination, an insulating block having parallel front and back faces with a passage leading from one face to the other, said passage at the front face being of a size to accommodate a plug blade, said passage being larger below the front face, a contact spring having a bowed portion in said enlargement, a substantially U shaped end on said spring, a further enlargement in said passage at the back face to receive said spring end, a terminal contact, a wing thereon fitting in said further enlargement and pressing both ends of said bowed portion of said spring against a wall of said passage, and an insulation sheet closing the back end of said passage and retaining the spring and terminal in position.

4. In a flush receptacle adapted to receive a plug having a fiat blade, in combination, an insulating block having parallel front and back faces with a passage leading from one face to the other, said passage at the front face being of a size to accommodate a plug blade, said passage 125 being larger below the front face, a contact springhaving a bowed portion in said enlargement, an end on said spring substantially at right angles to the chord of the bowed end, an insulation sheet to close the back end of said passage, said 130 sheet having a slot therein with said spring passing therethrough with the end resting on the outer surface of said sheet, a mounting strap for said block passing over said sheet, said strap contacting with and retaining said spring and sheet in position.

5. In a flush receptacle adapted to receive a plug having a flat blade, in combination, an insulating block having parallel front and back faces with a passage leading from one face to 1 the other, said passage at the front face being of a size to accommodate a plug blade, said passage being larger below the front face, a contact spring having a bowed portion in said enlargein position.

6. In a flush receptacle adapted to receive a plug having a fiat blade, in combination, an insulating block having parallel front and back faces with a passage leading from one face to the other, said passage at the front face being of a size to accommodate a plug blade, said passage being larger below the front face, a contact spring having a bowed portion in said enlargement, an end on said spring substantially at right angles to the chord of the bowed end and extending parallel to the back surface of said block, a metal mounting strap for said insulation block passing across the'back face thereof, an eyelet projecting from said back, said strap and spring end being perforated and fitted over said eyelet and said eyelet being riveted to retain both in position and in electrical engagement.

7. In a flush receptacle in combination, an insulation block having substantially parallel front and rear faces, said block having three passages therethrough between said faces, spring contacts in said passages extending to the back of said block, a terminal contact for each of two of said spring contacts, each on a side face of said block and each having spring engagement with its contact spring, an end on said third contact spring extending above and parallel to said rear face of said block, an insulation sheet covering said passages at the rear face and retaining said first two contact springs and terminals in position, said sheet having a slot therein, said third spring passing through said slot and extending along the outer face of the sheet, a mounting strap secured to said block, retaining said sheet in position and contacting with and holding said third spring in position.

8. In a flush receptacle, in combination an insulating block, a face thereon adapted to project through a flush plate, said block having three passages therethrough opening on said face, a rear face on said block having a shallow depression therein with said passages opening at the bottom thereof, springs in two of said passages adapted to engage the prongs of a standard attachment plug, binding terminals for said springs exposed at the sides of said block, a spring in said 4 trical contact and the strap retaining said spring third passage, an insulation sheet filling said shallow depression and closing the rear ends of said passages, a slit in said sheet through which said spring in said third passage passes and a mounting strap secured to said block retaining said sheet in position and electrically contacting with said last mentioned spring.

9. In combination, a wallbox, a bracket in the wallbox, a receptacle in the bracket having an opening, a clip from the bracket extending into the opening.

10. A device of the class described including, in combination, a wallbox, a bracket mounted in the wallbox and connected thereto, a clip on the bracket, a receptacle mounted in the bracket and having an opening to receive the clip, and circuit clips mounted in the receptacle.

11. A device of the class described comprising a bracket, means for mounting the bracket in a wallbox, a receptacle mounted in the bracket, said receptacle having an opening, a clip on the bracket extending into the opening.

12. A device of the class described including, in combination, a wallbox, a U-shaped strap bracket having terminal extensions fixed to the edge of the wallbox to dispose the bracket interiorly thereof, a receptacle in the U-shaped strap bracket having an opening, a clip projecting from the bight of the U-shaped strap bracket into the 0 'opening.

13. A device of the class described including, in combination, a wallbox, a U-shaped strap bracket having terminal extensions fixed to the edge of the wallbox to dispose the bracket interiorly thereof, a receptacle in the U-shaped strap bracket having an opening, a clip projecting from the bight of the U -shaped strap bracket into the opening, other clips mounted in openings in the receptacle.

14. A device of the class described comprising a U-shaped strap bracket having terminal outwardly disposed extensions adapted to be secured to the edge of a wallbox, a receptacle in the U- shaped strap bracket, said receptacle having an opening, a spring clip extending from the bight of the bracket through the opening.

MARK N. RUSSELL. 

